Antibacterial dry cleaning system

ABSTRACT

The invention provides a method of adding ozone to a solvent in a dry cleaning machine into the solvent line at the point where the solvent is leaving the solvent pump. The recirculated solvent in the dryer is furnished with ozone from an ozone generator for providing bacticidal and fungicidal effects. The present invention renders the dry cleaning procedures employed into more sanitary processes. The addition of ozone to the cleaning solvent prevents the establishment of bacteria or fungi colonies in a dry cleaning machine.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a method of dry cleaning textiles which arewashed with solvent and dried by hot air, the solvent being recoveredafter condensation.

2. Brief Description of the Background of the Invention Including PriorArt

With the ban on HCFCs and the sharp decline in the public acceptance ofper(tetra)chloroethylene, dry cleaning systems intended for hydrocarbonsolvents, i.e. very largely aroma-free solvents which are members of thealkane group, are becoming increasingly important. The flash point ofthese solvents is above 55.degree. C. Some of these solvents arenon-toxic solvents and are therefore subject to providing breedinggrounds for bacteria and fungi colonies.

Dry cleaning machines operate as a closed system and are responsible notonly for cleaning goods but also for drying them, at the same time asthey recover the solvent employed by condensing and regenerating it(distillation, adsorption). It is strongly desired that such drycleaning machines do not contaminate the clothes cleaned with bacteriaor fungi.

The use of flammable hydrocarbon solvents with their low vapor pressuresand high boiling ranges has created new requirements which the dryingprocess needs to meet with regard to optimum fire safety conditions, todrying times, to the use of energy and to the environment. It isstrongly desired that such solvents remain free from contamination.

Drying in dry cleaning systems is affected by a large number of varyingconditions: these are the nature and quantity of the goods to be cleanedand the amount of residual solvent left in them after spin drying, thephysical properties of the solvent used, the thermal energy applied andthe volume flow of the recirculated air. These conditions vary from oneload to the next. When there are large amounts of clothes to be cleanedthere is always the danger that a detrimental organism is carried fromone piece of clothes to another piece of clothes during the dry cleaningoperation.

Hitherto the drying process in dry cleaning systems has been controlledby time and the temperature of the recirculated air using empiricalvalues, which the machine operator presets at his own discretion. Theconsequences of controlling the process in this way are either:overdrying of the goods due to excessively long drying times, resultingin possible damage to the goods, excessive energy consumption and areduction in the machine's handling capacity, or insufficient drying dueto excessively short drying times, with the result that the goods arenot dried sufficiently well and the residual solvent gives rise toadditional emissions and may, under certain circumstances if in contactwith the skin for fairly long periods, cause skin irritation. Anyadditional irritation of the skin by bacteria or fungi transferredduring dry cleaning is undesirable.

This problem is of particular concern from the environmental and healthpoints of view because what tends to be found in practice, due toinadequate measuring and sanitary techniques and economicconsiderations, is underdrying rather than overdrying. An antibacterialsystem is desirable which does not interfere with the drying process ofa dry cleaning machine.

Also, with flammable solvents, there may be conditions in which theconcentration in the recirculated air in the drying system rises abovethe lower explosive limit. To avoid fires or explosions, primary safetymeasures are taken. The removal of bacteria and fungi from clothes to bedry cleaned should not interfere with the safety of the dry cleaningoperation.

SUMMARY OF THE INVENTION

1. Purposes of the Invention

The object of the invention on the other hand is to avoid on the onehand the cost and complications occurring in the past based on bacteriaor fungi infestations in dry cleaning apparatus. The recirculatedsolvent in the dryer is furnished with ozone from an ozone generator forproviding bacticidal and fungicidal effects. The present inventionrenders the dry cleaning procedures employed into more sanitaryprocesses.

These and other objects and advantages of the present invention willbecome evident from the description which follows.

2. Brief Description of the Invention

The present invention provides a method of adding ozone to a solvent ina dry cleaning machine into the solvent line at the point where thesolvent is leaving the solvent pump.

The addition of ozone to the cleaning solvent prevents the establishmentof bacteria or fungi colonies in a dry cleaning machine.

The novel features which are considered as characteristic for theinvention are set forth in the appended claims. The invention itself,however, both as to its construction and its method of operation,together with additional objects and advantages thereof, will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

In the accompanying drawing, in which are shown several of the variouspossible embodiments of the present invention:

FIG. 1 is a view of a schematic diagram illustrating the operation andconstruction of a dry cleaning machine with ozone generator,

FIG. 2 is a view of a schematic diagram illustrating a second embodimentof the invention,

FIG. 3 is a view of a flow diagram showing the process steps.

DESCRIPTION OF INVENTION AND PREFERRED EMBODIMENT

Ozone is generated by ultraviolet radiation. Ozone (O₃) is generated byirradiating air or oxygen (O₂) with ultraviolet radiation. Ozone is amolecule of oxygen that is formed when three atoms of oxygen are boundtogether instead of the normal two atoms. The additional oxygen atomrenders ozone a most powerful oxidizer and/or sanitizer readilyavailable.

Ozone is employed as a bacteria killer in accordance with the presentinvention.

Ozone operates essentially as an oxidizer. When ozone is used inoxidizes a large portion of any contaminants, bacteria, fungi. Ozonefurthermore disinfects. When ozone decomposes it does not leave anyresidue with the exception of regular oxygen molecules (O2).

Since ozone is unstable and quickly decomposes to regular oxygen underthe ambient conditions, ozone cannot be shipped or stored. Ozone istherefore produced at the location of use and for immediate use. Thelifetime of ozone in standard air is about an hour. In the solvent of adry cleaning machine the lifetime of ozone is shorter, but sufficient topurify and sanitize the solvent.

An ozone generator is connected to the solvent line. The ozone generatorcan preferably be switched on together with the solvent pump such thatthe ozone generator is running when the solvent pump is running. Theozonization will occur when the solvent pump is running.

The ozone generation is based on electrical power. The ozone generatorcomprises an ultraviolet lamp powered by electrical current. The lightof the ultraviolet lamp is directed to a chamber containing air or beingflown through by air. The interaction of the ultraviolet radiation withthe air in the chamber converts part of the oxygen in the air into ozonemolecules. If a sufficient number of regular oxygen molecules has beenconverted into ozone, then the air in the chamber containing the ozoneis lead out of the chamber and fed to the solvent of the dry cleaningapparatus.

The ozone generator produces ozone when air is drawn across a highenergy vacuum ultraviolet lamp for converting some air to ozone.

The electrical power employed for the ultraviolet lamp of the ozonegenerator can be standard electrical grid voltage of for example 120volts or 240 volts.

Generally the ozone generator 105 will contain a gas pump for moving theozone containing air from the irradiation chamber to the solvent pipe.The gas pump is preferably powered by electricity.

The hose for leading the ozone containing air from the chamber to thesolvent can be from about 1 mm to 2 cm diameter and preferably is of adiameter of from about 0.5 to 1 cm. A quarter inch hose will usuallyserve well for leading the ozone containing air from the ozonegenerating chamber to the pipe containing and transporting the solvent.Preferably a ¼ in check valve 101 is placed in the ozone conducting pipe107 for avoiding the possibility of solvent flowing back to the ozonegenerator.

The ozone is introduced into the solvent by an injector 103 either bydirect diffusion (sparging) or with a bypass Venturi system. When directdiffusion is employed the ozone containing air is forced through aporous metal disk, which creates extremely fine bubbles of ozonecontaining air. As the bubbles move into the solvent, the ozone is todisperse into the solvent where the ozone is able to react with bacteriaand fungi. If the ozone is introduced through an air Venturi pipesuitable for passing ozone, then bubbles of ozone are generated at theoutlet end of the air Venturi pipe.

The ozone generator should be mounted on a solid surface with a wood orsheet metal screws.

Suitable ozone generators are those which are commercially available forexample in connection with ozone water purification systems. The ozonegenerator can be of the type sold by Prozone International, Inc.

The solvent can be a hydrocarbon solvent, a silicon solvent, Rynex,Perc, alcohol, pentyl-acetate, siloxane solvent.

The use of nontoxic solvents can be associated and lead to bacteriagrowth. The solvents employed for dry cleaning in the cleaning processcan be chlorinated solvents, organic solvents, alcohols, esters,ketones, hydrocarbon solvents, perfluorocarbons, hydrofluorocarbons,volatile solvents, methyl siloxanes, monoclorotoluene,benzotrifluorides. Preferred solvents include chlorinated solvents,alcohols, esters, ketones, hydrocarbon solvents, siloxanes,monoclorotoluene, benzotrifluorides.

The solvent is pumped by the pump 109. The temperature of the solvent isadjusted in a heat exchanger 111 and then fed in four branches to valvesV7, V8, V9 and V12.

The valve V7 leads to the filter 1. The valve V7 allows the solvent toget to the drum across through filter 1.

The valve V8 leads to the filter 2. The valve V8 allows the solvent toget to the drum across through filter 2. The filter 1 is connected tothe filter 2.

The valve V9 and the valve V 10 allow the solvent to get to the drumbypassing the filter 1 and the filter 2.

The valve V11 connects a button trap or bottom trap to the solvent pump.

The valve V12 allows the solvent to get to the drum across a carbonfilter.

The valve V13 controls the drive of the brush in the button trap.

The valve V1 controls the connection from the tank 2 to the solvent pump109.

The valve V2 connects the tank 2 to the solvent pump.

The valve V3 connects the solvent pump to the tank 3 to allow for tankcleaning.

The valve V4 connects to the tank 2 and controls feeding the tank 2.

The valve V5 connects to the tank 1 and controls feeding the tank 2.

The valve V6 connects to the tank 3 and controls feeding the tank 2.

The valve VL allows for feeding the distillation process from tank 3.

The pump VP powers and feeds a distillation circuit.

A water separator WA is provided for separating water from the cleaningsolvent.

The draining distillation DA is connected to the ventilationdistillation DB.

The valve DD controls the steam supply to the distillation. The valve DTcontrols the steam supply to the steam heater and to the drying process.The valve DT is connected to the condenser K.

The waste air is exhausted by an air exhauster KA1.

Ventilation of the apparatus is furnished by the ventilator KA2 disposednear the condenser K. A valve KD is provided for the cooling water.

An impregnation dosing pump RV is furnished to adjust the amount ofimpregnant to be furnished during the cleaning process.

A soap dosing pump SP is furnished to adjust the amount of soap to befurnished during the cleaning process.

The heat exchanger FC10 is employed for heat exchange in connection withdistilling the solvent. The heat exchanger FC12 is employed inconnection with furnishing an appropriate temperature to the solvent.

The elements Y16-Y53 provide output lines from the PLC and arecontrolling the valves.

A safety lock TV is provided for locking the door of the dry cleaningmachine.

Mode of Operation

Solvent is furnished to tank T1 shown in FIG. 2. The solvent istransported out of the tank T1 with a solvent pump P1. Ozone isgenerated in the ozone generator 105 and fed through ozone conductingpipe 107 and through check valve 101 to the line junction with theinjector 103 to be mixed with the solvent stream coming from the solventpump P1. The mixture of solvent and ozone is feed through the heatexchanger 11 serving as a solvent cooler. The mixture is then fedthrough valves V9 and V10 to the drum D. An upper discharge of the drumD for substantially gaseous components leads to a lint filter LF forcatching lint. The filter part of the lint filter is removable and canbe cleaned or replaced. The gaseous discharge of the drum is then fedthrough a condenser C. The resulting condensate is transported to awater separator W. The solvent separated in the water separator W isthen returned to one of the tanks T1, T2 or T3 through a respectivevalve V4, V5 or V6.

The gaseous discharge of the condenser C is sucked up by a blower B andtransported to a heater H. The heated gaseous medium mostly consistingof hot air is then returned from the heater H to the drum D.

A lower discharge port of the drum D is mostly concerned with solid andliquids collected in the drum. The lower discharge port is connected toa button trap BT for separating solid particles and buttons. Thedischarge of the button trap BT is returned through valve V11 to thesolvent tanks T1, T2, T3 or to the solvent pump P1.

A part of the solvent in tank T3 is fed through the heat exchanger FC12and the valve VL to the distilling container S. The distillate from thedistilling container S is fed through a vacuum pump P2 and a heatexchanger FC10 to the solvent tank T2.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofdry cleaning system configurations and cleaning processing proceduresdiffering from the types described above.

While the invention has been illustrated and described as embodied inthe context of an antibacterial dry cleaning system, it is not intendedto be limited to the details shown, since various modifications andstructural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

1. A method for dry cleaning textiles comprising the steps of: pumping asolvent with a solvent pump; adding ozone to the solvent; washing saidtextiles with a solvent; drying said textiles using hot air;continuously measuring throughout the whole of said drying of saidtextiles, a concentration level of said solvent; measuring continuouslythroughout the whole of said drying of said textiles, a temperature ofsaid drying hot air; and recovering said solvent after condensation. 2.A dry cleaning apparatus comprising a tank for a solvent; a first lineconnected to the tank; a solvent pump connected tot he first line; asecond line connected to the solvent pump for receiving the output ofthe solvent pump; an injector attached to the second line for injectingozone into the solvent; a third line connected to the injector forfeeding ozone to the injector; a check valve connected to the thirdline; a fourth line connected to the check valve; an ozone generatorconnected to the fourth line; a drum for cleaning clothes connected tothe second line.